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A superfast unmanned military plane traveled at 20 times the
speed of sound and managed to control itself for three minutes
before crashing into the Pacific Ocean in a recent test, military
officials said.

The prototype
Falcon Hypersonic Technology Vehicle 2 (HTV-2), billed as the
fastest aircraft ever built, splashed down in the Pacific earlier
than planned on Aug. 11 shortly after launching from California's
Vandenberg Air Force Base on its second-ever test flight.

The HTV-2 experienced some sort of anomaly, prompting the
vehicle's autonomous flight safety system to guide it to a
controlled splashdown, according to the Defense Advanced Research
Projects Agency (DARPA), which oversaw the flight.

"HTV-2 demonstrated stable, aerodynamically controlled Mach 20
hypersonic flight for approximately three minutes," said DARPA
director Regina Dugan in an Aug. 14 statement. "We do not yet
know the cause of the anomaly for Flight 2."

The HTV-2 is part of an advanced weapons program called
Conventional Prompt Global Strike, which is working to develop
systems to reach an enemy target anywhere in the world within one
hour. It launches on a rocket, then comes streaking back to Earth
at enormous speeds, at times heating up to temperatures of nearly
3,500 degrees Fahrenheit.

DARPA officials said last week that the Aug. 11 test flight
collected more than nine minutes of data during the entire
mission.

An analysis conducted by an independent engineering review board
prompted engineers to adjust the HTV-2's center of gravity and
make several other changes before the second test. Those fixes
apparently corrected the first problem, officials said.

"An initial assessment indicates that the Flight 2 anomaly is
unrelated to the Flight 1 anomaly," said Air Force Maj. Chris
Schulz, DARPA HTV-2 program manager.

Another independent review board will look into what went wrong
with the second flight test in the coming weeks, DARPA officials
said.

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